1. Field of the Invention
The present invention relates to a method and an apparatus for three dimensional display with cross section used in such apparatuses as medical apparatuses and industrial measurement apparatuses.
2. Description of the Background Art
Recent progress in a field of computer graphics made a real time display possible, and is prompting the increasing usage of three dimensional display which is more realistic than two dimensional display.
In the three dimensional display, it is known to be effective to show a cross section at a specified cutting plane, so that the three dimensional display is often shown with cross section.
In such a three dimensional display with cross section, if a cross section is displayed in such a manner that those portions of an object which are closer to a viewer than a cutting plane are erased so that the cross sectional face is left open, the other portions of the object behind the cutting plane become visible and the cutting edge becomes obscure.
For this reason, in the three dimensional display, the cross sectional face is also treated as a surface and is displayed as being painted out in a prescribed color.
However, in displaying such an object with cross section three dimensionally, it has conventionally been necessary to produce surface data representing the object with the cross sectional face as a part of surface for each cross section, so that when the cutting plane is to be changed, a great amount of time has been required in obtaining the new surface data.